Measurement system with relative pose adjustment function and working method thereof

Abstract

The present application relates to the field of measuring instrument metrology testing technology, and particularly relates to a measuring system with relative position adjustment function and a working method thereof.The present application comprises a dual-frequency laser and a fiber coupling unit for providing light reference and voltage reference for a measuring unit; the measuring unit is used for providing measuring light to a sine arm; when there is a relative position deviation between the sine arm and the measuring unit, the light spot on the four-quadrant detector in the measuring unit will deviate from the center position and output the relative position deviation information between the sine arm and the measuring unit; when there is a relative angle deviation between the sine arm and the measuring unit, the light spot on the position sensitive detector in the measuring unit will deviate from the center position and output the angle deviation information between the sine arm and the measuring unit. Through the relative position monitoring system, the present application can realize the micron-level relative position adjustment precision and the angle-second-level relative angle adjustment precision between the sine arm and the measuring system.

Description

Technical Field

[0001] This invention relates to the field of measurement instrument metrology and testing technology, and in particular to a measurement system with relative posture adjustment function and its working method. Background Technology

[0002] In today's era of rapid technological advancement, the demands for precision in angle measurement are constantly increasing in high-precision manufacturing and scientific research. High-precision angle measurement plays a crucial role in many fields, such as precision machining, aerospace, and military communications.

[0003] In the production process of military equipment, the precision requirements for the machining of components are extremely high. Even a tiny angular deviation can lead to a decrease in the performance of the entire product or even its failure. For example, in aerospace equipment, the precise control of the angles of critical components such as aircraft wings and engine blades directly affects the flight performance and safety of the aircraft. In the manufacturing of military equipment, aiming systems for guns and cannons, pointing systems for radar, and other systems also require high-precision angle measurements to ensure their combat effectiveness.

[0004] In routine verification and calibration work, a large number of angle measuring instruments and equipment are widely used. Common examples include photoelectric autocollimators, which measure angles using the principle of optical autocollimation and are widely used in the processing and testing of optical components; electronic theodolites, used to measure horizontal and vertical angles, are indispensable in fields such as geodesy and engineering surveying; and electronic levels, which can accurately measure the horizontal and verticality of a plane and have important applications in industries such as machinery manufacturing and construction. In addition, the calibration of subdivided angles using a series of angle measuring devices, such as multi-tooth indexing tables, indexing heads, and inertial testing equipment, is also involved.

[0005] From a traceability perspective, to ensure the accuracy and reliability of various angle measuring instruments, high-level instruments are needed to pass down angle values. However, existing traditional small-angle measurement systems have certain limitations. One prominent problem is the lack of zero-point indication functionality. Zero-point indication is crucial for measurement systems, as it is key to determining the measurement start point and reference. The lack of zero-point indication makes it difficult to accurately determine the starting position during measurement, increasing the possibility of measurement errors and affecting the accuracy of the results.

[0006] Furthermore, existing small-angle measurement systems suffer from poor ease of installation and commissioning. Due to the complexity of the system's structure and operating principles, precise adjustment of the relative positions and orientations of various components is required during installation to ensure measurement accuracy. However, traditional systems often lack effective methods for monitoring and adjusting relative pose, making installation and commissioning time-consuming and labor-intensive, and demanding a high level of expertise from operators. This not only reduces work efficiency but also increases operating costs and the risk of human error. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a measurement system and its working method with relative pose adjustment function, which improves the accuracy of small angle measurement and the ease of installation and debugging, and meets the needs of high-precision manufacturing and scientific research for angle measurement.

[0008] To achieve the above and other related objectives, the present invention provides a measurement system with relative pose adjustment function, comprising:

[0009] A dual-frequency laser and fiber optic coupling unit are used to provide optical and voltage references for the measurement unit.

[0010] A measurement unit is used to provide measurement light to the sine arm. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm.

[0011] A sine arm, which is connected to the device for generating the angle to be measured;

[0012] A host computer is connected to the output end of the dual-frequency laser and the fiber optic coupling unit. The host computer is used to display the angle and position information output by the measurement unit.

[0013] In one embodiment of the present invention, the dual-frequency laser and fiber coupling unit include: a He-Ne dual-frequency laser, a coupling lens C-Lens, a fiber coupling mechanism, and a polarization-maintaining fiber PMF. The He-Ne dual-frequency laser is used to output orthogonally linearly polarized light. The orthogonally linearly polarized light passes through the coupling lens C-Lens and the fiber coupling mechanism in sequence and enters the polarization-maintaining fiber PMF before being output to the measurement unit.

[0014] In one embodiment of the present invention, the measuring unit includes:

[0015] A collimating lens is used to receive the orthogonally linearly polarized light output from the polarization-maintaining fiber PMF and convert it into collimated parallel light.

[0016] The collimated parallel light passes through the first beam splitter, and its reflected light sequentially passes through the first polarizer and the first lens to form interference, and is received by the first detector; the transmitted light from the first beam splitter enters the second beam splitter again, and its reflected light enters the relative pose monitoring subsystem.

[0017] The second beam splitter, after the transmitted light passes through the half-wave plate and enters the first polarizing beam splitter, its transmitted light is reflected back into the first polarizing beam splitter by the first cornerstone prism.

[0018] The first polarizing beam splitter has its reflected light passing through the first mirror and then entering the second cornerstone prism. After reflection, the light returns to the first polarizing beam splitter and merges with the reflected light from the first cornerstone prism. The merged light then passes through the second polarizer and the second lens in sequence to produce interference and is received by the second detector.

[0019] The signals obtained by the first detector and the second detector are used to calculate the relative angle change between the sinusoidal arm and the measuring unit.

[0020] In one embodiment of the present invention, the measuring unit further includes:

[0021] A half-wave plate is set in the relative pose monitoring subsystem. After the orthogonally linearly polarized light passes through the half-wave plate, it enters the second polarizing beam splitter. Its transmitted light passes through the second reflecting mirror and enters the third corner cube prism. After reflection, it returns to the four-quadrant detector and is used to monitor the relative position change between the measurement unit and the sine arm.

[0022] The second polarizing beam splitter reflects linearly polarized light. After passing through a quarter-wave plate, the linearly polarized light becomes circularly polarized and illuminates a third reflecting mirror. After being reflected by the third reflecting mirror, it passes through a quarter-wave plate again, becoming linearly polarized. The polarization direction of the linearly polarized light is orthogonal to the original polarization direction. After passing through the quarter-wave plate a second time, the linearly polarized light is transmitted through the second polarizing beam splitter, then through a fourth reflecting mirror and a lens, and illuminates a position-sensitive detector to monitor the relative angle change between the measurement unit and the sine arm.

[0023] In one embodiment of the present invention, the sine arm is composed of both mechanical and optical structures. Specifically, the sine arm includes a sine arm body and a first corner prism, a second corner prism, a third corner prism, and a third reflector disposed in the sine arm body.

[0024] In one embodiment of the present invention, the host computer is also used to connect to a serial port module.

[0025] In one embodiment of the present invention, the host computer is also used to connect a USB module.

[0026] The present invention also provides a method for operating a measurement system with relative pose adjustment function, comprising:

[0027] S1. A dual-frequency laser and fiber optic coupling unit provide optical and voltage references for the measurement unit;

[0028] S2. A measurement beam is provided to the sine arm through the measurement unit. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm.

[0029] S3. The angle and position information of the measurement unit are received and converted by the dual-frequency laser and fiber optic coupling unit.

[0030] S4. Display the angle and position information via a host computer.

[0031] In one embodiment of the present invention, in step S2, the measurement unit provides measurement light to the sine arm. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm, including:

[0032] S21. The orthogonally linearly polarized light output from the polarization-maintaining fiber PMF is received through a collimating lens and converted into collimated parallel light.

[0033] S22. The collimated parallel light passes through the first beam splitter, and its reflected light passes through the first polarizer and the first lens in sequence to form interference, and is received by the first detector; the transmitted light from the first beam splitter enters the second beam splitter again, and its reflected light enters the relative pose monitoring subsystem.

[0034] S23. After the transmitted light passes through the half-wave plate and enters the first polarizing beam splitter, its transmitted light is reflected back into the first polarizing beam splitter by the first cornerstone prism.

[0035] S24. The reflected light from the first polarizing beam splitter enters the second cornerstone prism after passing through the first reflecting mirror. After reflection, it returns to the first polarizing beam splitter and merges with the reflected light from the first cornerstone prism. The merged light then passes through the second polarizer and the second lens in sequence to produce interference and is received by the second detector.

[0036] S25. The signals obtained by the first detector and the second detector are used to calculate the relative angle change between the sinusoidal arm and the measuring unit.

[0037] In one embodiment of the present invention, step S2, in which the measuring unit provides measuring light to the sine arm, when there is a relative positional deviation between the sine arm and the measuring unit, the light spot on the four-quadrant detector in the measuring unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measuring unit, the light spot on the position-sensitive detector in the measuring unit will deviate from the center position and output the angular information of the sine arm further includes:

[0038] S26. The orthogonally linearly polarized light passes through a half-wave plate and enters a second polarizing beam splitter. Its transmitted light passes through a second reflecting mirror and enters a third cornerstone prism. After reflection, it returns to a four-quadrant detector to monitor the relative position change between the measurement unit and the sine arm.

[0039] S27. The reflected light from the second polarizing beam splitter is linearly polarized. After passing through a quarter-wave plate, the linearly polarized light becomes circularly polarized and illuminates the third mirror. After being reflected by the third mirror, it passes through a quarter-wave plate again, and the circularly polarized light becomes linearly polarized. The polarization direction of the linearly polarized light is orthogonal to the original polarization direction. After passing through the quarter-wave plate twice, the linearly polarized light is transmitted through the second polarizing beam splitter, and after passing through the fourth mirror and lens, it illuminates the position-sensitive detector to monitor the relative angle change between the measurement unit and the sine arm.

[0040] As described above, the measurement system and its working method with relative pose adjustment function of the present invention have the following beneficial effects:

[0041] (1) The measurement system with relative pose adjustment function of the present invention adopts a technical route that combines the laser heterodyne interferometry principle and the laser collimation measurement principle, which can quickly and accurately equip the small angle measurement system to the angle generating device to be measured. Through the relative pose monitoring system, the relative position adjustment accuracy between the sine arm and the measurement system at the micrometer level and the relative angle adjustment accuracy at the arcsecond level can be achieved.

[0042] (2) The measurement system with relative pose adjustment function of the present invention provides a strong guarantee for the accuracy and reliability of the measurement results, and provides solid and reliable measurement data support for precision manufacturing, large-scale device assembly and high-end scientific research, greatly reducing the risk of production accidents and experimental deviations caused by measurement errors.

[0043] (3) The measurement system with relative pose adjustment function of the present invention provides an accurate and standardized standard for the traceability of measurement values ​​of angle measuring instruments and equipment in actual use. This enables the measurement values ​​of angle measuring instruments and equipment to be uniformly traced to the standard system established by this standard system, avoiding inaccurate and unreliable measurement values, ensuring good consistency and comparability of measurement results at different times, locations, and instruments, and improving the credibility and effectiveness of measurement data across the entire industry. Attached Figure Description

[0044] Figure 1 A schematic diagram of a measurement system with relative pose adjustment function provided in an embodiment of this application;

[0045] Figure 2 A measurement principle diagram of a measurement system with relative pose adjustment function provided in an embodiment of this application;

[0046] Figure 3 A structural diagram of a sinusoidal arm and a measuring unit of a measuring system with relative pose adjustment function provided in an embodiment of this application;

[0047] Figure 4 This is a structural diagram of a dual-frequency laser and fiber optic coupling unit for a measurement system with relative pose adjustment function provided in an embodiment of this application. Detailed Implementation

[0048] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0049] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0050] Terms such as "first" or "second" may be used to describe various components, but these components are not limited by the terms described above. The terms described above are used to distinguish one component from another; for example, without departing from the scope of the concept according to this disclosure, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

[0051] Furthermore, "connected / linked" indicates that one component is directly electrically connected to another component or indirectly electrically connected through another component. Unless otherwise explicitly stated in the sentence, the singular form may include the plural form. Additionally, the terms "comprising / including" or "containing / including" as used in this specification indicate the presence or addition of one or more components, steps, operations, and elements. Specific structural or functional descriptions of examples of embodiments of the concepts disclosed in this specification are merely illustrative to describe examples of embodiments of the concepts, and examples of embodiments of the concepts can be implemented in various forms, but these descriptions are not limited to the examples of embodiments described in this specification.

[0052] Based on the concept, various modifications and changes can be applied to examples of embodiments, such that examples of embodiments will be illustrated in the accompanying drawings and described in the specification. However, examples of embodiments based on the concept are not limited to specific embodiments, but include all changes, equivalents, or substitutions included within the spirit and scope of this disclosure.

[0053] It should be understood that when describing an element as "connected" or "linked" to another element, the element may be directly connected or linked to the other element, or it may be connected or linked to the other element via a third element. Conversely, it should be understood that when an element is described as "directly connected to" or "directly linked to" another element, no other element is placed between them. Other expressions describing relationships between components (i.e., "between" and "directly between" or "adjacent to" and "directly adjacent to") need to be interpreted in the same way.

[0054] The terminology used in this specification is for the purpose of describing specific examples of implementations only and is not intended to limit this disclosure. The singular form may include the plural form unless there is an explicit contrary meaning in the context. It should be understood in this specification that the terms "comprising" or "having" indicate the presence of the features, quantities, steps, operations, components, parts, or combinations thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, operations, components, parts, or combinations thereof.

[0055] Unless otherwise defined, all terms used herein (including technical or scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art. If a term is not clearly defined in a common dictionary in this specification, it shall be interpreted as having the same meaning as in the context of the relevant art, and not as an ideal or overly formal meaning.

[0056] Descriptions of known components and processing techniques may be omitted to avoid unnecessarily obscuring the embodiments of this disclosure.

[0057] Throughout this specification, the same reference numerals refer to the same elements. Therefore, even if a reference numeral is not mentioned or described with reference to one drawing, it may be mentioned or described with reference to another drawing. Furthermore, even if a reference numeral is not shown in one drawing, it may be mentioned or described with reference to another drawing.

[0058] Additionally, the logic level of a signal may be different from or opposite to the logic level described. For example, a signal described as having a logic "high" level may optionally have a logic "low" level, and a signal described as having a logic "low" level may optionally have a logic "high" level.

[0059] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0060] Please see Figure 1 , Figure 1This is a schematic diagram of a measurement system with relative pose adjustment function provided in an embodiment of this application. The present invention provides a measurement system with relative pose adjustment function, comprising: a dual-frequency laser and an optical fiber coupling unit for providing a light reference and a voltage reference to a measurement unit; a measurement unit for providing measurement light to a sine arm, wherein when there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm; the dual-frequency laser and the optical fiber coupling unit are also used to receive and convert the angular information and position information of the measurement unit; a host computer is connected to the output end of the dual-frequency laser and the optical fiber coupling unit, and the host computer is used to display the angular information and position information. Specifically, the signal transmitted by the measurement unit, which is the angle information and position information, is transmitted via RS485 to the dual-frequency laser and fiber optic coupling unit. The dual-frequency laser and fiber optic coupling unit converts the RS485 signal into a USB signal, which is then displayed by the host computer.

[0061] In one embodiment of the present invention, a high-precision small-angle measurement system with relative pose adjustment function employs the laser heterodyne interferometry principle for small-angle measurement to ensure measurement accuracy. Based on the laser heterodyne interferometry subsystem, and based on the principles of laser collimation and self-collimation, an innovative relative pose monitoring subsystem between the sinusoidal arm and the measurement unit is proposed. The two subsystems are organically combined to form a novel high-precision small-angle measurement unit with relative pose adjustment function.

[0062] Please see Figure 2 , Figure 2 This is a schematic diagram of a measurement system with relative pose adjustment function provided in an embodiment of this application. The dual-frequency laser and fiber coupling unit include: a He-Ne dual-frequency laser, a coupling lens C-Lens, a fiber coupling mechanism, and a polarization-maintaining fiber PMF. The He-Ne dual-frequency laser outputs orthogonally linearly polarized light, which sequentially passes through the coupling lens C-Lens and the fiber coupling mechanism into the polarization-maintaining fiber PMF, and is then output to the measurement unit.

[0063] Specifically, the measurement unit includes: a collimating lens for receiving orthogonally linearly polarized light output from the polarization-maintaining fiber PMF and converting it into collimated parallel light; a first beam splitter, through which the collimated parallel light passes, and its reflected light sequentially passes through a first polarizer and a first lens to form interference, and is received by a first detector; the transmitted light from the first beam splitter re-enters a second beam splitter, and its reflected light enters a relative pose monitoring subsystem; a second beam splitter, through which the transmitted light passes through a half-wave plate and enters a first polarizing beam splitter, and its transmitted light is reflected back to the first polarizing beam splitter by a first pyramidal prism; a first polarizing beam splitter, through which the reflected light passes through a first reflecting mirror, enters a second pyramidal prism, is reflected back to the first polarizing beam splitter, and merges with the reflected light from the first pyramidal prism, and the merged light sequentially passes through a second polarizer and a second lens to generate interference, and is received by a second detector; and a first detector and a second detector, whose signals are used to calculate the relative angle change between the sinusoidal arm and the measurement unit.

[0064] The measurement unit further includes: a half-wave plate disposed in the relative pose monitoring subsystem; the orthogonal linearly polarized light passes through the half-wave plate and enters the second polarizing beam splitter; its transmitted light passes through the second reflecting mirror and enters the third cornerstone prism; after reflection, it returns to the four-quadrant detector, used to monitor the relative position change between the measurement unit and the sine arm; a second polarizing beam splitter; the reflected light from the second polarizing beam splitter is linearly polarized light; the linearly polarized light passes through a quarter-wave plate and becomes circularly polarized light, and then illuminates the third reflecting mirror; after reflection by the third reflecting mirror, it passes through the quarter-wave plate again, and the circularly polarized light becomes linearly polarized light. The polarization direction of the linearly polarized light is orthogonal to the original polarization direction; after passing through the quarter-wave plate a second time, the linearly polarized light passes through the second polarizing beam splitter, and then through the fourth reflecting mirror and lens, illuminates the position-sensitive detector, used to monitor the relative angle change between the measurement unit and the sine arm.

[0065] In one embodiment of the present invention, the measurement system with relative pose adjustment function of the present invention performs high-precision small-angle measurements based on the principle of laser heterodyne interferometry. This method can improve measurement sensitivity, resolution, and accuracy by increasing the distance between measurement ray 1 and measurement ray 2. Based on the principle of laser collimation, a high-precision two-degree-of-freedom relative position monitoring method is proposed. The measurement ray illuminates the corner prism in the relative pose monitoring subsystem and returns to the four-quadrant detector in the measurement unit. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector will deviate from the center position. This position information is transmitted to the host computer software for real-time display after photoelectric conversion. By adjusting the position of the sine arm, the light spot on the four-quadrant detector returns to the center position, at which point the laser small-angle measurement unit is in the ideal position. Based on the principle of laser self-collimation, a high-precision two-degree-of-freedom relative angle monitoring method is proposed. The measurement ray illuminates the reflector in the relative pose monitoring subsystem and returns to the position-sensitive detector in the measurement unit. When there is a relative angleal deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector will deviate from the center position. This position information is transmitted to the host computer software for real-time display after photoelectric conversion. By adjusting the angle of the sine arm, the light spot on the position-sensitive detector returns to the center position, at which point the laser small-angle measurement unit is in the ideal position. In summary, the relative pose adjustment function proposed in this patent enables the small-angle measurement unit to achieve higher repeatability and assembly accuracy. Furthermore, it significantly improves the assembly efficiency for users.

[0066] In one embodiment of the invention, a dual-frequency laser outputs orthogonally linearly polarized light, which enters a single-mode polarization-maintaining fiber through a coupling mirror. A half-wave plate is used to align the fast and slow axes of the polarization-maintaining fiber. The orthogonally linearly polarized light output from the polarization-maintaining fiber passes through a collimating mirror in the measurement unit, becoming collimated parallel light. After passing through the first beam splitter, its reflected light passes through a polarizer and a lens, forming interference, and is received by a detector. The transmitted light from the first beam splitter enters the second beam splitter again. Its reflected light enters the relative pose monitoring subsystem, the optical path of which is described later. The transmitted light from the second beam splitter passes through a half-wave plate and enters a polarizing beam splitter prism. Its transmitted light is reflected by a cornerstone prism and returns to the polarizing beam splitter prism. The reflected light from the polarizing beam splitter passes through a reflecting mirror and enters another cornerstone prism. After reflection, it also returns to the polarizing beam splitter prism and merges with the reflected light from the first cornerstone prism. The merged light passes through a polarizer and a lens, interfering, and is received by a detector. The signals obtained by the two detectors described above can be used to calculate the relative angular change between the sinusoidal arm and the measurement unit. In the relative pose monitoring subsystem, orthogonally linearly polarized light passes through a half-wave plate and then enters a polarizing beam splitter. Its transmitted light passes through a mirror and then enters a cornerstone prism. After reflection, it returns to the four-quadrant detector in the measurement unit to monitor the relative position change between the measurement unit and the sinusoidal arm. The reflected light from the polarizing beam splitter is linearly polarized. This linearly polarized light passes through a quarter-wave plate and becomes circularly polarized, then illuminates the mirror. After reflection, it passes through another quarter-wave plate, becoming linearly polarized again, but this time the polarization direction is orthogonal to the previous polarization direction. Therefore, the linearly polarized light, after passing through the quarter-wave plate twice, passes through the polarizing beam splitter, then through a mirror and lens, and illuminates the position-sensitive detector to monitor the relative angular change between the measurement unit and the sinusoidal arm.

[0067] Please see Figure 3 , Figure 4 , Figure 3 A structural diagram of a sinusoidal arm and a measuring unit of a measuring system with relative pose adjustment function provided in an embodiment of this application; Figure 4This diagram illustrates the structure of a dual-frequency laser and fiber optic coupling unit for a measurement system with relative pose adjustment capabilities, as provided in this application embodiment. The dual-frequency laser and fiber optic coupling unit provide a high-quality light reference with stable frequency, power, and polarization direction for the entire measurement system. It also provides a stable voltage reference for the photodetector drive circuit and data processing and transmission circuit within the measurement unit. It consists of a He-Ne dual-frequency laser, a polarization-maintaining fiber (PMF), a coupling lens (C-Lens), and a fiber optic coupling mechanism. The He-Ne dual-frequency laser, as the light source of the measurement system, possesses stable frequency, polarization direction, and output power, providing a good reference for error measurement. A specially designed high-resolution, high-stability, and compact 4DOF fiber optic coupling mechanism couples the orthogonally linearly polarized light output from the dual-frequency laser into the single-mode polarization-maintaining fiber through the coupling lens group (C-Lens).

[0068] The measurement unit is the core functional unit of a high-precision small-angle measurement unit with relative pose adjustment capabilities. It is the identification unit for small angles and relative pose deviations. Based on the principles and methods of small-angle measurement and relative pose deviation monitoring, and taking into account the function and size of the measurement unit, the optical system, circuit system, and mechanical structure of the measurement unit are designed as a whole.

[0069] The sine arm is the core component of the small-angle measurement unit, serving as a reflector and line-angle converter in the optical path. It has corner prisms mounted at both ends, and the distance between the optical vertices of the corner prisms is the arm length. According to the sine principle formula, increasing the arm length improves the system's angular resolution. Furthermore, the sine arm also incorporates corner prisms and reflectors serving the relative pose monitoring subsystem.

[0070] Table 1: Technical Specifications of High-Precision Small-Angle Measurement Unit with Relative Pose Adjustment Function

[0071]

[0072]

[0073] Set up the sine arm on the multi-tooth indexing stage to be tested, and adjust the relative pose between the measuring unit and the sine arm so that the spot positions on the four-quadrant detector and the position-sensitive detector in the relative pose monitoring system are at zero. At this point, the sine arm and the measuring unit are successfully matched. The small-angle system performs a zeroing operation. Then, the calibration steps for the multi-tooth indexing stage can be carried out.

[0074] Similar to the principle of the measurement system with relative pose adjustment function of the present invention, the present invention also provides a method for operating the measurement system with relative pose adjustment function, comprising:

[0075] S1. A dual-frequency laser and fiber optic coupling unit provide optical and voltage references for the measurement unit;

[0076] S2. A measurement beam is provided to the sine arm through the measurement unit. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm.

[0077] S3. The angle and position information of the measurement unit are received and converted by the dual-frequency laser and fiber optic coupling unit.

[0078] S4. Display the angle and position information via a host computer.

[0079] In step S2, the measurement unit provides measurement light to the sine arm. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm. When there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm, including:

[0080] S21. The orthogonally linearly polarized light output from the polarization-maintaining fiber PMF is received through a collimating lens and converted into collimated parallel light.

[0081] S22. The collimated parallel light passes through the first beam splitter, and its reflected light passes through the first polarizer and the first lens in sequence to form interference, and is received by the first detector; the transmitted light from the first beam splitter enters the second beam splitter again, and its reflected light enters the relative pose monitoring subsystem.

[0082] S23. After the transmitted light passes through the half-wave plate and enters the first polarizing beam splitter, its transmitted light is reflected back into the first polarizing beam splitter by the first cornerstone prism.

[0083] S24. The reflected light from the first polarizing beam splitter enters the second cornerstone prism after passing through the first reflecting mirror. After reflection, it returns to the first polarizing beam splitter and merges with the reflected light from the first cornerstone prism. The merged light then passes through the second polarizer and the second lens in sequence to produce interference and is received by the second detector.

[0084] S25. The signals obtained by the first detector and the second detector are used to calculate the relative angle change between the sinusoidal arm and the measuring unit.

[0085] In step S2, the measurement unit provides measurement light to the sine arm. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm. When there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm. This step further includes:

[0086] S26. The orthogonally linearly polarized light passes through a half-wave plate and enters a second polarizing beam splitter. Its transmitted light passes through a second reflecting mirror and enters a third cornerstone prism. After reflection, it returns to a four-quadrant detector to monitor the relative position change between the measurement unit and the sine arm.

[0087] S27. The reflected light from the second polarizing beam splitter is linearly polarized. After passing through a quarter-wave plate, the linearly polarized light becomes circularly polarized and illuminates the third mirror. After being reflected by the third mirror, it passes through a quarter-wave plate again, and the circularly polarized light becomes linearly polarized. The polarization direction of the linearly polarized light is orthogonal to the original polarization direction. After passing through the quarter-wave plate twice, the linearly polarized light is transmitted through the second polarizing beam splitter, and after passing through the fourth mirror and lens, it illuminates the position-sensitive detector to monitor the relative angle change between the measurement unit and the sine arm.

[0088] In summary, the measurement system with relative pose adjustment function of this invention adopts a technical approach combining the principles of laser heterodyne interferometry and laser collimation measurement, enabling the rapid and high-precision integration of a small-angle measurement system into the angle generation device. Through the relative pose monitoring system, micron-level relative position adjustment accuracy and arcsecond-level relative angle adjustment accuracy between the sine arm and the measurement system can be achieved. The accuracy and reliability of the measurement results of this invention are strongly guaranteed, providing solid and reliable measurement data support for precision manufacturing, large-scale device assembly, and high-end scientific research, significantly reducing the risk of production accidents and experimental deviations caused by measurement errors.

[0089] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A measurement system with relative pose adjustment function, characterized in that, include: A dual-frequency laser and fiber optic coupling unit are used to provide optical and voltage references for the measurement unit; A measurement unit is used to provide measurement light to the sinusoidal arm. The measurement unit includes a laser heterodyne interferometry small-angle measurement subsystem and a relative pose monitoring subsystem. The laser heterodyne interferometry measurement subsystem includes a first detector and a second detector. The signals obtained by the first and second detectors are used to calculate the relative angle change between the sinusoidal arm and the measurement unit. The relative pose monitoring subsystem includes a four-quadrant detector and a position-sensitive detector. The four-quadrant detector monitors the relative position change between the measurement unit and the sinusoidal arm, and the position-sensitive detector monitors the relative angle change between the measurement unit and the sinusoidal arm. When there is a relative positional deviation between the sinusoidal arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sinusoidal arm; when there is a relative angle deviation between the sinusoidal arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angle information of the sinusoidal arm. A sine arm, which is connected to the device for generating the angle to be measured; The dual-frequency laser and fiber optic coupling unit are also used to receive and convert the angle information and position information of the measurement unit; A host computer is connected to the output end of the dual-frequency laser and the fiber optic coupling unit. The host computer is used to display the angle information and position information. The measurement unit includes: A collimating lens is used to receive orthogonally linearly polarized light output from a polarization-maintaining fiber PMF and convert it into collimated parallel light; The collimated parallel light passes through the first beam splitter, and its reflected light sequentially passes through the first polarizer and the first lens to form interference, and is received by the first detector. The transmitted light from the first beam splitter enters the second beam splitter, and its reflected light enters the relative pose monitoring subsystem. The second beam splitter receives transmitted light that passes through a half-wave plate and enters the first polarizing beam splitter. The transmitted light is then reflected back into the first polarizing beam splitter by a first pyramidal prism. The first polarizing beam splitter has its reflected light passing through the first mirror and then entering the second cornerstone prism. After reflection, the light returns to the first polarizing beam splitter and merges with the reflected light from the first cornerstone prism. The merged light then passes through the second polarizer and the second lens in sequence to produce interference and is received by the second detector. A half-wave plate is installed in the relative pose monitoring subsystem. Orthogonally linearly polarized light passes through the half-wave plate and enters the second polarizing beam splitter. Its transmitted light passes through the second reflecting mirror and enters the third cornerstone prism. After reflection, it returns to the four-quadrant detector. The second polarizing beam splitter reflects linearly polarized light. After passing through a quarter-wave plate, the linearly polarized light becomes circularly polarized light and illuminates the third mirror. After being reflected by the third mirror, it passes through a quarter-wave plate again, and the circularly polarized light becomes linearly polarized light. The polarization direction of the linearly polarized light is orthogonal to the original polarization direction. After passing through the quarter-wave plate a second time, the linearly polarized light is transmitted through the second polarizing beam splitter, and then through a fourth mirror and lens, it illuminates the position-sensitive detector. The sine arm includes a sine arm body and a first corner prism, a second corner prism, a third corner prism, and a third reflecting mirror disposed in the sine arm body.

2. The measurement system with relative pose adjustment function according to claim 1, characterized in that, The dual-frequency laser and fiber coupling unit include: a He-Ne dual-frequency laser, a coupling lens C-Lens, a fiber coupling mechanism, and a polarization-maintaining fiber PMF. The He-Ne dual-frequency laser is used to output orthogonally linearly polarized light. The orthogonally linearly polarized light passes through the coupling lens C-Lens and the fiber coupling mechanism in sequence, enters the polarization-maintaining fiber PMF, and is then output to the measurement unit.

3. The measurement system with relative pose adjustment function according to claim 1, characterized in that... The host computer is also used to connect to the serial port module.

4. The measurement system with relative pose adjustment function according to claim 1, characterized in that... The host computer is also used to connect to a USB module.

5. A method for operating a measurement system with relative pose adjustment function as described in any one of claims 1 to 4, characterized in that, include: S1. A dual-frequency laser and fiber optic coupling unit provide optical and voltage references for the measurement unit; S2. A measurement beam is provided to the sine arm through the measurement unit. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm. S3. The angle and position information of the measurement unit are received and converted through the dual-frequency laser and fiber optic coupling unit; S4. Display the angle and position information via a host computer; In step S2, the measurement unit provides measurement light to the sine arm. When there is a relative positional deviation between the sine arm and the measurement unit, the light spot on the four-quadrant detector in the measurement unit will deviate from the center position and output the position information of the sine arm; when there is a relative angular deviation between the sine arm and the measurement unit, the light spot on the position-sensitive detector in the measurement unit will deviate from the center position and output the angular information of the sine arm, including: S21. The orthogonally linearly polarized light output from the polarization-maintaining fiber PMF is received through a collimating lens and converted into collimated parallel light; S22. The collimated parallel light passes through the first beam splitter, and its reflected light sequentially passes through the first polarizer and the first lens to form interference, and is received by the first detector; the transmitted light from the first beam splitter enters the second beam splitter again, and its reflected light enters the relative pose monitoring subsystem; S23. After the transmitted light passes through the half-wave plate and enters the first polarizing beam splitter, its transmitted light is reflected back into the first polarizing beam splitter by the first cornerstone prism. S24. The reflected light from the first polarizing beam splitter passes through the first reflecting mirror, enters the second cornerstone prism, and after reflection, returns to the first polarizing beam splitter, where it merges with the reflected light from the first cornerstone prism. The merged light then passes through the second polarizer and the second lens in sequence, causing interference, and is received by the second detector. S25. The signals obtained by the first detector and the second detector are used to calculate the relative angle change between the sinusoidal arm and the measurement unit. S26. The orthogonally linearly polarized light passes through a half-wave plate and enters a second polarizing beam splitter. Its transmitted light passes through a second reflecting mirror and enters a third cornerstone prism. After reflection, it returns to a four-quadrant detector to monitor the relative position change between the measurement unit and the sine arm. S27. The reflected light from the second polarizing beam splitter is linearly polarized. After passing through a quarter-wave plate, the linearly polarized light becomes circularly polarized and illuminates the third reflecting mirror. After being reflected by the third reflecting mirror, it passes through a quarter-wave plate again, and the circularly polarized light becomes linearly polarized. The polarization direction of the linearly polarized light is orthogonal to the original polarization direction. After passing through the quarter-wave plate a second time, the linearly polarized light is transmitted through the second polarizing beam splitter, and after passing through the fourth reflecting mirror and lens, it illuminates the position-sensitive detector to monitor the relative angle change between the measurement unit and the sine arm.

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